In a communication system, data switching apparatus is needed to convert a source data transmitted from the previous circuit into an output data to be used by subsequent circuit for data processing. Data switching apparatus is just like a translation system between previous circuit and the subsequent circuit, the previous circuit needs a data-switching apparatus to convert source data into output data that can be controlled by the subsequent circuit before data processing can be performed by the subsequent circuit. Therefore, it is indispensable no matter in the transmitter or the receiver of communication system. Here, the output data is generated by shifting the source data. Note that, the communication specification it supports has to be decided and needs to match the above-mentioned previous circuit processing and data transmission. For example, IEEE 802.16e Worldwide Interoperability for Microwave Access (WiMax), IEEE802.11n, Digital Video Broadcasting (DVB), 4th generation mobile communication (4G) and Ultra-Wideband (UWB), etc. Therefore, all the source data received by data switching apparatus should match the coding dimension as specified by the communication specification.
In conventional data switching apparatus, since data shifting is needed to achieve the purpose of converting the source data transmitted from the previous circuit into output data; therefore, shifter circuit is needed to perform the operation of shifting data. Conventional shifter circuit is designed with data shifting data component, that is, multiple numbers of multiplexers are used to move the source data. Each multiplexer is connected to the data of two neighboring bit in source data and the last multiplexer is connected to the highest bit and the lowest bit of the source data; then through the by controlling the multiplexer, and complete the shifting operation of source data. However, the number of multiplexer is related to the coding dimension and each communication specification has multiple sizes of coding dimensions; moreover, all the coding dimension are different, take the WiMax) as an example, it has 19 sizes of coding dimensions for the LDPC (Low Density Parity Check) encoder and decoder, thus, the above-mentioned coding dimensions of source data are all different. Therefore, in conventional data switching apparatus, the shifter circuit design in dealing with fixed size of coding dimensions which the architecture includes one fixed size shifter circuit and perform only single coding dimension, that is, it is not allowed to use the same shifter circuit to shift source data according to multiple sizes of coding dimension.
Take WiMax as an example, if all the 19 sizes of coding dimensions specified by WiMax LDPC code are to be used in the communication production, data switching apparatus should be implemented using a circuit comprising of 19 different sizes shifters to process corresponding data for 19 sizes of coding dimensions respectively. The electronic circuit will occupy pretty large chip area and the complexity of hardware design will be relatively increased too. Furthermore, the manufacturing cost is relatively increased too.
Therefore, it is highly expected that a multi-size coding dimensions data switching apparatus for communication system that reduces circuit area and hardware complexity can be invented.